Current plumbing materials are typically made from lead containing copper alloys. One standard brass alloy formulation is referred to in the art as C84400 or the “81,3,7,9” alloy (consisting of 81% copper, 3% tin, 7% lead, and 9% zinc) (herein in after the “81 alloy”). While there has been a need, due to health and environmental issues (as dictated, in part, by the U.S. Environmental Protection Agency on maximum lead content in copper alloys for drinking water applications) and also for cost reasons, to reduce lead contained in plumbing fitting, the presence of lead has continued to be necessary to achieve the desired properties of the alloy. For example, the presence of lead in a brass alloy provides for desirable mechanical characteristics and assists in machining and finishing the casting. Simple removal of lead or reduction below certain levels substantially degrades the machinability as well as the structural integrity of the casting and is not practicable.
Removal or reduction of lead from brass alloys has been attempted previously. Such previous attempts in the art of substituting other elements in place of lead has resulted in major machining and finishing issues in the manufacturing process, which includes primary casting, primary machining, secondary machining, polishing, plating, and mechanical assembly.
Several low or no lead formulations have previously been described. See, for example, products sold under the trade names SeBiLOY® or EnviroBrass®, Federalloy®, Biwalite™, Eco Brass®, Bismuth Red Brass (C89833), and Bismuth Bronze (C89836) as well as U.S. Pat. Nos. 7,056,396 and 6,413,330. FIG. 1 is a table that includes the formulation of several known alloys based upon their registration with the Copper Development Association. The existing art for low lead or no lead copper based castings consists of two major categories: silicon based materials and bismuth/selenium materials.
However, there is a need for a low-lead solution providing a low-cost alloy with similar properties to current copper/lead alloys without degradation of mechanical properties or chemical properties, as well as significant disruption to the manufacturing process because of lead substitution in the material causing cutting tool and finishing problems.